Image by Kenzoka via Flickr
Arrange for mail to be held or collected by neighbors. Let your neighbors know if you are going to be away.
If you have a Smartphone, you do not need your laptop. Your Smartphone will do Facebook/Skype/Email just fine on your hotel's wifi, and if they don't have wifi at the very least you could go to McDonalds and buy some fries to leech off their wifi for a bit I guess
Don’t forget all documents - passports, licenses, travel insurance, tickets, a pen and notebook as well as your travel money
Plastic bags. They take up no space, and I guarantee you'll be glad you have them. I save my plastic grocery bags, and always bring a few of them in my luggage. They are amazingly useful when backpacking. I use them to segregate dirty clothes from clean, for makeshift waterproofing when I'm stuck in the rain, for wrapping food, or to disguise a camera while walking around a city.
If carrying on your summer holiday gifts, be sure to check and see which items need batteries as their power source. Nothing is worse than giving a battery operated gift without the batteries included, especially when gifting to little ones.
Add some glam to your summer wardrobe, and make your outfits sizzle!!...it's effortless with this custom-made floppy hat!!
A couple of things I try to keep at hand, in addition to what is already mentioned:
Pen + small notepad
A roll of toilet paper
Small bottle of anti-bac
Shoes: Lose the hiking boots, please. Flip-flops and decent sneakers (preferably decent enough to even get into a club) are more than enough for 99% of the trips
Love good soap? I mean REALLY GOOD soap? We have a deal for you! Here is a chance to score five large 5 oz. bars of our all-natural vegan cold process castile soap in a flat rate priority box to save on shipping!
A Sealed Soap dish. You don't want to have to buy a new bar of soap every time you leave the hostel/hotel. Get a sealed dish, and you'll be able to keep your things from getting all soapy in your bag, and will always have soap on the go.
Entertainment from books to MP3 players, portable DVDs to games and toys depending on your travel group. And don't forget your mobile phones and cameras
Rechargeable batteries and charger, I find these to be pretty handy, and help save money. no explanation necessary.
Travel and holiday outdoor clothing, protective clothing and everything you would need for walking trips, camping holidays, backpacking and trekking expeditions
Appropriate clothing for your destinations. For city holidays, don't forget the all- important comfortable walking shoes.
Travel is like any other addiction which you just can’t get enough of,! I do agree that it is an expensive affair, but if you put in a little time and effort, the internet has the cheapest and the best deals to offer. Most of my holidays have been meticulously planned over weeks (to ensure we do not exceed our minimal budget!!), and I must say that it just adds to the overall experience!
Prescription medicines and a copy of the prescription in case you loose your bags. If you need glasses to see make sure you have a back up: an old pair, contacts or prescription sunglasses.